Update the gclient config instructions to not use relative paths.
Update the gclient config instructions to not use relative paths.

As of https://codereview.chromium.org/1406053003 relative paths are no
longer valid for the solution name.  Update the docs to use the full
current directory instead.

BUG=angleproject:1204

Change-Id: I42b289fdad6d85901f431bb701f2a08e0ad0deb3
Reviewed-on: https://chromium-review.googlesource.com/311180
Reviewed-by: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>
Tested-by: Geoff Lang <b6fc25fe0362055230985c05cbfa8adb741ccc0f@chromium.org>

mlfarrell/angle,domokit/waterfall,ppy/angle,ecoal95/angle,domokit/waterfall,MSOpenTech/angle,mikolalysenko/angle,ecoal95/angle,ppy/angle,ppy/angle,ecoal95/angle,MSOpenTech/angle,MSOpenTech/angle,mikolalysenko/angle,ecoal95/angle,ecoal95/angle,mlfarrell/angle,mikolalysenko/angle,mikolalysenko/angle,mlfarrell/angle,mlfarrell/angle,ppy/angle,MSOpenTech/angle